The Correct Way to Dice an Onion

Think you know how to dice an onion? If your method takes a time, effort, and tears, you’re doing it wrong. But guess what? There’s a better way!

You’re not alone if you get that sinking feeling anytime a recipe calls for dicing an onion. It takes a long time, and on top of that, they make you cry (why, onions, why?! Rowlf knows what I’m talking about…). Luckily, there’s a brilliant, speedy, onion dicing technique out there, and we’re going to show you exactly how to do it.

This technique has many advantages. Not only is it an easy way to dice an entire onion in less than a minute, it also reduces the chance of onion-y tears. By leaving the root intact and the open side of the onion down on the cutting board, you minimize the amount of propanethiol S-oxide released. This is the gas that reacts with the water in your eyes to form sulfuric acid, which burns and makes your cry (and thus ends the science portion of today’s lesson). Not to mention, if you dice an onion faster means less time your eyes are exposed to those stingy onion irritants.

How to Properly Dice an Onion

1. Things you need: large knife, cutting board, and of course, an onion.

onion

2. Cut the top off the onion, but leave the root intact.

chop the top

3. Slice the onion in half from the top to the root.

cut in half

4. Now you can easily remove the skin by grabbing the edge from the top and pulling down towards the root. Then just rip it off.

peel the skin

5. Place the onion flat side down, and hold it from the top. Place the knife parallel to the cutting board and slice toward the root. Be sure to stop cutting before you reach the root, so that the onion stays together.

(tip: pull the cutting board to the edge of the table, and hold the knife so that your hand is off the board. This allows you to cut the onion with a flat, parallel stroke. If your hand rests on the cutting board, the width of your fingers will tilt the handle of the knife up, leading to uneven cuts in the onion)

horizontal cuts

6. Make more parallel cuts all the way up the onion, so that you have multiple cuts. Again, never cut all the way through the root.

horizontal cuts done

7. Place the onion flat side down again. Make a vertical cut at the edge of the onion, without cutting through the root.

long vertical cuts

8. Continue making vertical cuts along the whole onion in the same fashion.

vertical cuts done

9. Now, before you dice the onion, make sure you won’t lop off a finger. Hold the onion with the tips of your fingers, creating a flat line down the fronts of your fingers. This way the knife will slide down your fingers; no stray fingertips in the way.

grip the onion

10. Holding the onion, flat side down, with the tips of your fingers, cut it in rows from the wide end to the root.

dice

As you make these final cuts, the whole onion will fall apart into a pile of small, evenly sized pieces. And all it took was about a dozen knife strokes, no need to finely chop each piece individually. And you can be assured your onions will cook evenly, since all the pieces will be the same size. This technique can also be used on other veggies, like shallots and even garlic.

Let us know how this technique works for you in the comments below.

Lauren is a New York based actor/singer/writer. She is a graduate of the American Repertory Theater/Moscow Art Theater School Institute for Advanced Theater Training at Harvard University as well as the College of the Holy Cross. She's a fan of beer, pasta, and academic establishments with unnecessarily long titles. Find her on stage, or online-- she's there often.